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Action agencies have encouraged the development of a modified electrical fish barrier system to deter upstream movements of California sea lions Zalophus californianus as a means to reduce their predation on returning adult Pacific salmon Oncorhynchus spp. within rivers along the West Coast of North America. Given that the barrier system does not discriminate which species will experience electrical shock, we studied the potential effects of the sea lion barrier on the survival, behavior, physiology, and injury of white sturgeon Acipenser transmontanus. Fish subjected to acute electroshock had high survival (100%). Conversely, fish that became entrained within the electric field and therefore experienced chronic electroshock had lower survival (93%). White sturgeon altered their behavior by spending significantly more time avoiding the area over the barrier when electrical power was applied as compared with controls. Fish that experienced acute electroshock spent more time remaining motionless, presumably recovering from physiological disturbance. Our results indicate that white sturgeon had significantly higher plasma lactate than controls and that lactate remained at elevated levels for at least 4 h after electroshock. Plasma glucose, ion concentrations (chloride, sodium, and potassium), and indicators of cell damage (plasma hemoglobin and enzyme activity of aspartate transaminase) did not differ between electroshocked fish and controls. We did not observe any notable hemorrhages or notochord injuries in white sturgeon that experienced electrical shock. Our results suggest that the location for the electrical barrier system should be rigorously examined before barrier deployment and that the dates, frequency, and duration of use should be further refined to ensure that negative effects on nontarget species such as white sturgeon are minimized.

Background: Acoustic transmitters used in telemetry studies to assess fish migration and survival are often surgically implanted into the coelomic cavity of the fish. While intra-coelomic implantation is a well-established method, the surgical process and/or implanted device may affect the health, behavior and survival of the fish under investigation, thus affecting study results. Tag effect research has focused on minimizing the aforementioned effects and continues to look for novel solutions. The first use of bi-directional knotless (barbed) suture material in fish occurred in 2009 to close incisions in juvenile Chinook salmon (Oncorhynchus tshawytscha). The suture barbs eliminate the need for knots, thereby reducing surgical time and concomitantly anesthetic and handling time for the fish. The bi-directional knotless suture had higher transmitter retention compared to the monofilament material, which was in a simple interrupted pattern. However, the incisions closed with bi-directional knotless sutures had an increased occurrence of ulceration and erythema. The objective of this study was to refine the suturing patterns of the bi-directional knotless suture used in 2009 by altering the needle size and retest suture performance in juvenile Chinook salmon. We examined the effects from the bi-directional knotless suture using three different suture patterns and two needle lengths: 6-Point (12-mm needle length), Wide "N" (12-mm needle length), Wide "N" Knot 12 (12-mm needle length), and Wide "N" Knot 18 (18-mm needle length). Results: Using a performance rank index of observed metrics (mortality, transmitter expulsion, suture functionality, incision openness, ulceration and erythema), the Wide "N" Knot 12 suture pattern had an overall better performance than the other needle types and suture patterns. All needle types and suture patterns resulted in poor suture functionality by Day 14. The 6-Point, Wide "N" and Wide "N" Knot 18 treatments had no functional sutures by the end of the study; while the Wide "N" Knot 12 treatment had 33% functional sutures.